Under-Loaded Board Operators Create Risk

NEWSLETTER ARTICLE

A theory/practice widely held in refineries is to keep
board operator workload low for steady state operation in
order to accommodate the typical step increase in
workload that occurs with upsets. This may not only be
ineffective, but also counter productive. It has long been
known that low levels of workload can negatively affect
operator performance. Recent research by Mark Young
and Neville Stanton indicates that the low workload
problem is both different and worse than previously
thought. (Young, M. and Stanton, N. “ Malleable
Attentional Resources Theory: A new explanation for the
effects of mental under load on performance”. Human
Factors, Vol. 44, No. 3, Fall 2002, P365-375)

The performance decrement with low workload has
typically been associated with a drop-off in vigilance,
which typically occurs after 20-30 minutes on the job.
Young and Stanton’s research indicates the problem is
more severe. An actual shrinking of available mental
workload resources (or mental reserve) is seen after only
10 minutes. Current workload theory has workload
resources being fixed or constant, but this came from data
looking at overload situations. The new research adds to
the old theory – yes, available mental workload resources
are limited/fixed in the short term, however they can and
do shrink.

Increasing automation and process stability has been
shown to reduce the workload on board/console operators
at most process plants. If staffing or span-of-control
changes are not implemented, under-loaded board
operators can result. If the new theory is true, should an
upset occur, the reduced workload resources make
responding to the upset more difficult than if the base
workload is higher. Good intentions of keeping the board
lightly loaded for upsets could potentially backfire,
actually increasing the probability of operator error at a
critical time.